That's the refrain a graying, creaky Arnold Schwarzenegger repeats throughout the new "Terminator" film, attempting to reassure his comrades that, though his machinery has aged, he can still get the job done.

The 67-year-old is seeking to disprove similar doubts after suffering a string of box-office flops following his exit from the California governor's office in 2011. On Wednesday, he'll reprise his most iconic role for the fourth time in "Terminator Genisys," the latest installment in the sci-fi franchise that helped to establish the actor as a big-screen action hero in the 1980s.

But the gears are showing some signs of rust. The $155-million production is projected to take in a disappointing $55 million during its first five days in theaters over the busy Fourth of July holiday. And many critics have panned the fifth film in the "Terminator" series — though Schwarzenegger's performance has been cited as one of the movie's few redeeming elements.

That performance could help "Genisys" beat box-office expectations. But only one of the three action films he's headlined since leaving office — "The Last Stand," "Escape Plan" and "Sabotage" — grossed even $25 million domestically. He's played a supporting role in the more successful "Expendables" franchise, but those films feature a handful of aging action stars, including Sylvester Stallone, Harrison Ford and Bruce Willis. Critics did warm to his more dramatic turn in the indie zombie flick "Maggie," but the film, which premiered at the Tribeca Film Festival this spring, was seen only in limited release.

The father of the "Terminator" franchise, James Cameron, has seen "Terminator Genisys," and despite the befuddling title, he is impressed. So impressed, in fact, that he made a video stating just that. But also in this video is a bit of new footage that reveals the Terminator vs. Terminator showdown,...

Hollywood is largely where Schwarzenegger has focused his efforts since his second term as governor concluded. He has remained nominally involved in the political world, three years ago launching the USC Schwarzenegger Institute, which allows him to be engaged with issues such as climate change or after-school programs.

But acting, his collaborators say, is where his true passion lies. He cares about being taken seriously as a performer and is sensitive to harsh critiques — even voicing his displeasure with The Times after it published a blog post about the commercial prospects for "Genisys."

"It matters to him to get critical acclaim and respect. We've had discussions about it," says Rob Stutzman, a Republican political consultant who served as Schwarzenegger's communications director from 2003 to 2006. Once, Stutzman recalled, a Starbucks barista complimented the actor on his 1994 comedy "Junior," which wasn't exactly a critical darling.

"I laughed, looked at Schwarzenegger and said, 'Ha! Never heard anyone say that,'" Stutzman says. "And then I got the Terminator glare. It was like, 'OK, note to self: He can make fun of the bad movies, but I can't.' He's self-aware and can be self-deprecating, but he's sensitive to criticism from others."

Despite Schwarzenegger's recent box-office misfires, the filmmakers behind "Genisys" insist they would not have even made the film without him. Director James Cameron's original 1984 "Terminator" introduced the actor's T-800 as a literal killing machine: an unstoppable, monosyllabic cyborg sent back in time on a mission to assassinate Linda Hamilton's Sarah Connor. In his smash 1991 sequel, Cameron flipped the script, making Schwarzenegger's Terminator the protector of Sarah's son, John — a function he also served, albeit less memorably, in 2003's "Terminator 3: Rise of the Machines." He didn't appear in 2009's "Terminator Salvation" because he was governor at the time, perhaps a wise decision since the film was both a critical and financial misfire.

This time around, his Terminator is softer — a protector of Sarah (Emilia Clarke) since her childhood — with robotic arthritis and wrinkled skin. He still has an arsenal of weapons, but its walls are lined with photos and sentimental mementos from Sarah's early days. David Ellison, whose Skydance Productions co-financed "Genisys" with distributor Paramount Pictures, said Schwarzenegger eagerly embraced the idea of Terminator aging.

"He loved having gray hair and the idea that the character was becoming more human," says the producer. "He didn't want this to be a retreat. There are other parts in franchises you can swap out; multiple actors have played Bond. But with Tom Cruise in 'Mission Impossible' and Schwarzenegger as Terminator, those are very special situations."

On set, Schwarzenegger was a jovial presence — cracking jokes and eating lunch every day with the crew, "which is almost unheard of in the movie star world," says director Alan Taylor. "But there was nothing more restorative to him."

Meanwhile, he worked hard to regain the bodybuilder physique he showed off in 1984. During the filming of the original "Terminator," he weighed 230 pounds; this time, he put on 10 pounds to hit 228 on the scale. Jason Clarke, who plays John Connor in the new version, says he often sat in the makeup trailer with his costar talking about everything from fitness to politics to cars to boots. Schwarzenegger even showed Clarke a picture of his "yearly boot polish," during which he polished 120 of his boots.

"He does everything with a wonderful sense of humor," Clarke says. "He's not an angry man or a disappointed man or a regretful man. He loves people."

Paramount has attempted to capitalize on Schwarzenegger's playful side in marketing "Genisys," even having him lend his unmistakable voice to the navigation commands on the app Waze and doing a comedy skit with Jimmy Fallon on "The Tonight Show."

Last Wednesday, he talked openly to Howard Stern about the affair with his maid that led to his divorce from Maria Shriver and, as he put it, "my fifth child."

"It's a very tough situation for my kids," Schwarzenegger told Stern. "It was tough for everybody. But it has happened, and now we have to figure it out, right?"

It remains to be seen if moviegoers will embrace the Governator's latest reinvention. And it's not just future "Terminator" sequels on the line: Schwarzenegger is also developing other reboots of old hits like "Twins" and "Conan the Barbarian," whose fate could be determined by his box-office clout.

The film's director, meanwhile, remains hopeful that "Genisys" will be the film to endear Schwarzenegger to the public yet again.

"Whether he was in a movie two weeks beforehand that did well or not, this is the Terminator, and it's his own thing," Taylor says. "Robert Downey Jr. can't do anything except 'Iron Man' these days. With any other movie, there's no connection with audiences. Some roles are just singular."